Steam-boiler furnace



Dec, 23, 1924.

w. A. GILCHRIST STEAM BOILER FURNACE Original Filed Feb. 8. 1919Patented Dec. 23, 1924.

WILLIAM A. GILGI-IRIST, OF NEW YORK, N. Y.

STEAM-BOILER FURNACE.

Application filed February 8, 1919, Serial No. 275,838. Renewed. March19, 1923.

' To all whom it may concern:

Be it known that I, WILLIAM A. GIL- oi-rnis'r, a citizen of the UnitedStates, and a resident of New York, county and State of New York, haveinvented certain new and useful Improvements in Steam-Boiler Furnaces,of which the following is a specification, and which are illustrated inthe accomanying drawings, forming a part thereof.

\Vhile it has long been recognized that loss of economy and theproduction of smoke may result when the combustion of furnace gases ischecked by contact with the relatively cool surfaces of a. steam boiler,adequate provision for insuring complete combustion of the gases evolvedfrom solid fuels has not heretofore been made without unduly restrictingthe furnace outlet or retardin destructive distillation in the fuel bed.When the fuel contains a relatively large proportion of volatileconstituents the effect of chilling the furnace gases by contact withthe boiler shell or tubes before coml'iustionhas been completed isreadily noticeable from the production of smoke. There is, however, anequally important loss of economy if the burning gases rising from solidfuel containing only small quantities of volatile constituents areallowed to come in contact with the boiler surfaces. While smoke may notresult in the last mentioned case, the chilling of the gases beforetheir combustion has been completed nevertheless result in the escape ofunconsumed combustible gas with a corresponding loss of economy. Itfollows that whether the flames principally comprise. burninghydrocarbonaceous gases rising from a bed of fuel containing largeproportions of volatile constituents or burning carbon monoxide risingfrom a bed of fuel containing only small amounts of volatileconstituents, greater economy will be secured if the construction of thefurnace is such as to provide ample time for the combustion of the gasesto be completed before they come in contact with the relatively coolsurfaces of the boiler.

The present invention accordingly relates to steam boiler furnaces andcontemplates a construction wherein the burning gases rising from thefuel travel over masonry walls entirely for such a distance be yond thefuel bed as to avoid any cooling of the gases by contact with the boileruntil sufli-cient time has elapsed for complete combustion of allinflammable ingredients. The object of the invention is to provide animproved steam boiler furnace wherein solid fuels may be burned withgreat economy and without the production of smoke, even though the fuelmay contain a large proportion of volatile constituents and moisture.The improved construction also provides that the fuel will be burnedwith such rapidity as to secure increased capacity from a plant of agiven size.

In the accompanying drawings Fig. 1 is a longitudinal sectional Viewshowing a furnace embodying the features of improvement provided by theinvention, one of the boilers associated therewith being1 conventionallyrepresented in elevation, anc

Fig. 2 is a transverse sectional view taken partly upon a planeextending centrally through the fire box of the furnace and partly upona plane extending through a combustion chaniber and upright flue locatedimmediately in rear of the said fire box.

For simplicity of illustration Figs. 1 and 2 of the drawings show anapplication of the improved furnace to the familiar type of returntubular boiler, two of which, as 10, 11, are provided. Inasmuch,however, as the exposed surfaces of all boilers are normally much coolerthan the ignition temperatures of combustiblegases, it will beundcrstood that boilers of any type present the same requirement thatcombustion of the furnace gases should be completed before they come incontact with the boiler, and that the invention is not limited inrespect to the type of boiler with which the improved furnace is to beused.

If desired, the two boilers 10, 11, may be arranged in a pair servedfrom a single fire box, as 12. In carrying out the invention, the firebox 12 is preferably extended in front of the boilers and is providedwith a masonry arch or roof 13. The grate 14 may be of the form commonlyemployed for supporting the particular kind of fuel intended to be usedand for admitting air for combustion through the same from the ash pit,as 15. As shown, the arch 13 and grade 1 1 extend continuously betweenthe side walls 16, 17, these being located to embrace the two boilers10, 11, with suitable flue spaces, as 18, 19, 20, between and at thesides of the boilers. The furnace front 21 is formed with the usualclean-out and firing doors, 22, 23, while, if saw-dust or the like is tobe used as fuel, the arch 13 will also be provided with feed openings,as 24, 25.

To permit a free escape of gases from the fire box chamber, the fire box12 is preferably wide open at its rear end throughout its entire widthand height. There is thus an unrestricted communication between thechamber of the fire box 12 and a combustion chamber 26 located in rearof the same. The floor 27 of the combustion chamber 26 is preferably onthe same level with the grate 14 but the boilers as 10, 11, on the otherhand, are desirably so located as to be not only a substantial distanceabove the floor 2'7 but also a substantial distance above the level ofthe arch 13. The furnace gases accordingly have a relatively long upwardtravel after entering the combustion chamber 26 and before coming incontact with the boiler shell.

Combustion of the gases within the chamber 26 will be stimulated if thecombustion chamber 26 is bounded at the rear by an upright masonry wall,as 28. Furthermore, if the fuel contains a large proportion of volatileconstituents, destructive distillation will also be stimulated if thewall 28 faces directly into the chamber of the fire box through its openrear end. This arrangement is also particularly effective in promotingthe rapid drying of a fuel which contains moisture. In any case, thewall 28 becomes highly heated, thereby promoting combustion of the gasesin the chamber 26 and, by radiation and reflection of heat, assisting inmaintaining a high temperature in the chamber of the fire box 12. Thisis desirable with solid fuel of any kind for it promotes rapidity ofcombustion and secures increased capacity for the plant.

In carrying out the present invention the Wall 28 (Fig. 1) is extended asubstantial distance above the level of the arch 13 to adjacent theunderside of the boiler, as 10, 11. The upper portion of this wallaccordingly forms, with the front wall 29 of the boiler setting and theadjacent portions of the side walls, 16, 17, a relatively long uprightflue 30 leading out of the combustion chamber 26. As the walls of theflue 30 are of masonry, a high temperature will be maintained within theflue and combustion of the gases during their upward travel will becontinued until all inflammable products have been consumed. It will, ofcourse, be understood that the top of the Wall 28 will preferably beseparated a sufficient distance from the underside of the boilers toprovide for the merging of the fines 18, 19, 20, under the boilers.

While the wall 28 will in all cases be located sufiiciently close to therear end of the fire box 12 for effective radiation of heat into thefire box chamber, its exact location may be varied in accordance withcertain properties of the fuel intended to be used. In event the fuelcontains moisture, as in the case of wet saw-dust, bagasse, peat orlignite, whereby the products of destructive distillation will belargely diluted with water vapor, the wall 28 will be so located as toprovide a larger combustion chamber 26 and flue 30 than will be requiredfor a fuel like bituminous coal from which only combustible gas isevolved. With dry fuel containing only a small proportion of volatileconstituents whereby the burning gases are not diluted with water vaporand con tain but little hydrocarbon, the wall 28 may be so located as tostill further reduce the size of the combustion chamber 26.v Theextension of the wall 28 above the level of the arch 13 not onlyprovides the upright flue St) leading out of the combustion chamber 26but it also substantially increases the amount of surface from whichheat will be radiated onto the fuel bed within the lire box.Furthermore, it will be observed that the increase in the amount ofsurface which is effective in radiating heat back into the fire box isproportioned to the distance at which the wall 28 is located from thefire box. It follows that when the wall 27 is so located as to provide alarge combustion chamber 26, as when the burning gases are diluted withwater vapor which has been evaporated from a wet fuel, the amount ofradiating surface which is effective for drying the fuel is alsoincreased.

The upright surface of the wall 28 is not only important for insuringreflection and radiation of heat upon the fuel bed but the constructionof the wall in this form also serves to prevent its being renderedineffective by accumulations of solid matter which may be carried overby the flames.

WVhilethe Walls 16, 17, 27, 28, and 29 and the arch 13 will usually becomposed of refractory clay products, commonly termed masonry, the useof the word masonry in the accompanying claim is not intended to imposeany limitation with respect to the particular composition of therefractory material employed, nor to the form in which it is used.Vertical enlargement of the combustion chamber 26, by its connectionwith the flue 30, which forms an extension of the said combustionchamber, permits of a relatively close location of the heat reflectingwall 28 to the fuel bed without corresponding reduction in the volume ofthe said combustion chamber. Likewise the substantial elevation of theboilers as 10, 11 above the fuel bed and the provision of the extendedflue 30 between the combustion chamber 26 and the boiler she-ll,substantially prevent loss of heat from the fuel bed by direct radiationupon the boiler. This is of special importance in the use of low gradefuel since it is otherwise difficult to maintain sufiiciently highfurnace temperatures for rapid drying and destructive distillation ofthese fuels.

I claim as my invention:

1. In a steam boiler furnace, in combination, a grate for supporting thefuel bed, a masonry arch and masonry side walls extending over and aboutthe grate and form ing therewith a fire box which is closed except atits rear end where it is open for substantially its entire width andheight, a forwardly facing upright masonry wall beyond the rear end ofthe arch but adjacent the open end of the fire box and extendingsubstantially from the grate level to and a substantial distance abovethe level of the said arch, a horizontal upwardly facing imperforatemasonry floor extending substantially at the grate level from the rearend of the grate to the said upright masonry wall and constituting thefloor of a combustion chamber having a direct commumcation with thechamber of the fire-box through the open rear end of the same, a boilerset ting comprising masonry side walls and an upright masonry front wallextending upwardly from the rear end of the said arch and forming withthe first mentioned up right masonry wall and the adjacent portions ofthe side walls of the setting an upward extension of the said combustionchamber within which the furnace gases are completely protected fromcontact with the boiler shell.

2. In a steam boiler furnace, in combination, a grate for supporting afuel bed, a masonry arch and masonry side walls extending over and aboutthe grate and forming therewith a fire-box closed except at its rear endwhere it is open for substantially its entire width and height, aforwardly facing upright masonry wall beyond the rear end of the archbut adjacent the open end of the fire-box and extending fromsubstantially the grate level to and a substantial distance above thelevel of the arch, a horizontal upwardly facing imperforate masonryfloor extending substantially at the grate level from the rear end ofthe grate to the upright masonry wall, a second upright masonry wallextending upwardly from the rear end of the arch, and masonry side wallsforming with said floor and upright walls a. combustion chamber havingdirect communication with the fire-box through the open rear end thereofand extending substantially above the level of the rear end of the archand in which the furnace gases will be completely protected from contactwith a boiler shell.

3. In a steam boiler furnace, in combination, a grate for supporting afuel bed, a masonry arch and masonry side walls extending over and aboutthe grate and forming therewith a fire-box closed except at its rear endwhere it is open for substantially its entire width and height, aforwardly facing upright masonry wall beyond the rear end of the archbut adjacent the open end of the fire-box, a horizontal upwardly facingimperforate masonry floor extending substantially at the grate levelfrom the rear end of the grate to the upright masonry wall, and masonryside walls forming with said floor and upright wall a combustion chamberhaving direct communication with the fire-box through the open rear endthereof, the combustion chamber having an extension within which thefurnace gases will be completely protected from contact with a boilershell.

4. In a steam boiler furnace, in combination, a. fire-box having a gratefor support ing a fuel bed and a masonry arch over the grate, thefire-box being open at its rear end for substantially its entire widthand height, a forwardly facing masonry wall beyond the rear end of thearch extending upwardly from substantially the level of the rear end ofthe grate, and masonry walls forming with said forwardly facing wall acombustion chamber having direct communication with the fire-box throughthe open rear end thereof and extending substantially above the level ofthe rear end of the arch and in which the furnace gases will beprotected from contact with a boiler shell until combustion issubstantially complete.

5. In a furnace, in combination, a grate, a masonry arch extending overthe grate, the said arch constituting the roof of a fire box chamberwhich is open at its rear end throughout the width of the grate and archand from substantially the level of the rear end of the grate to thearch, an upright transverse masonry heat storage and reflecting wallextending from substantially the level of the rear end of the grate tothe level of the rear end of the arch but located beyond the rear endsof the grate and arch and facing directly into the fire box chamber, anupwardly facing 'masonary floor extending between the grate and the saidupright masonry wall substantially at the level of the rear end of thegrate and constituting with the said upright wall the floor and endrespectively of a combination chamber adjoining the fire box andcommunicating directly therewith through the open rear end of the same,and masonry walls confining a fine forming an extension of thesaidcombustion chamher and leading to a steam boiler or the like, thelast mentioned masonry wall springing, respectively, from the upper endof the first mentioned upright wall and from the rear end of the arch.

6. In a furnace, in combination, a grate, a

flat masonry arch extending over the grate, the said arch constitutingthe roof of a fire box chamber which is open at its rear end throughoutthe width of the grate and arch and from substantially the level of therear speotively of a combustion chamber adjoina ing the fire box andcommunicating directly therewith through the open rear end of the same,and masonry walls confining a flue forming an extension of the saidcombustion chamber and leading to a steam boiler or the like, the lastmentioned masonry walls springing respectively from the upper end of thefirst mentioned upright wall and from the rear end of the arch.

7. In a furnace, in combination, a flathorizontal grate for supportingthe fuel bed, a flat masonry arch extending over the grate, the saidarch constituting the roof of a fire box chamber which is open at itsrear end throughout the width of the grate and arch and from the gratelevel to the level of the rear end of the arch, an upright transversemasonry heat storage and reflecting wall extending from the grate levelto and a substantial distance above the plane of the arch but locatedbeyond the rear ends of the grate and arch and facing directly into thefire box chamber, an upwardly facing masonry floor extending at thegrate level from the rear end of the grate to the said upright wall andconstituting wit-h the latter the floor and end, respectively, of acombustion chamber adjoining the fire box and communicating directlytherewith through the open rear end of the same, and'a masonry wallrising from the rear end of the arch and constituting with the saidupward extension of the first mentioned upright wall the front and rearwalls: respectively of a fine forming a continuation of the saidcombustion chamber and leading to a steam boiler or the like.

8. In a furnace, in combination, a grate for supporting the fuel bed, amasonry arch extending over the grate, the said arch constituting theroof of a fire box chamber which is open at its rear end throughout thewidth of the grate and arch and from the grate level to the level of therear end of the arch, an upright transverse masonry heat storage andreflecting wall extending from the grate level to and a substantialdistance above the plane of the arch but located beyond the rear ends ofthe grate and arch and facing directly into the fire box chamber, anupwardly facing masonry floor extending at the grate level from the rearend of the gate to the said upright wall and constituting with thelatter the floor and end respectively of a combustion chamber adjoiningthe fire box and communicating directly therewith through the open rearend of the same, and a masonry wall rising from the rear end of the archand constituting with the said upward extension of the first mentionedupright wall the front and rear walls respectively of a flue forming acontinuation of the said combustion chamber and leading to a steamboiler or the like.

VILLIAM A. GILC I-IRIST.

